THE MELON FLY IN HAW AIL 39 



HABITS. 



The larvae immediately upon hatching within the egg cavity or 

 puncture begin to feed upon the surrounding tissues of the host. 

 In one instance only were they observed to desert the host through 

 the punctured epidermis. In this instance the eggs from which they 

 hatched had been deposited under forced laboratory conditions in 

 a firm-textured apple, which is not ordinarily a host fruit. The larvae 

 on hatching deserted this fruit only to die on the exterior a short 

 distance from the point of emergence. 



Ordinarily the young larvae begin immediately, to burrow into the 

 pulp of the host, and in the case of many fruits they burrow at once 

 to the center, where they feed until well grown. When the fruits 

 are of a watery texture, or of a very firm texture, the larvae prefer 

 or are forced to feed near the epidermis. In decayed spots in toma- 

 toes or cucumbers and like fruits, which have become filled with rain 

 water, the larvae come to the surface for varying intervals and re- 

 main in rather dense formation, each larva perpendicular to the 

 moisture level, with its posterior spiracles protruding. In this po- 

 sition the mass of larvae remains very quiet unless disturbed. All 

 larvae are forced to come to the surface for air unless their tunnels 

 are formed within a host sufficiently free from excess moisture to 

 permit air to penetrate freely the larval channels. When hatching 

 from eggs deposited in open wounds in well-developed pumpkins or 

 squashes, the larvae find it impossible to penetrate to the interior, 

 but are able to make full development in the outer portion. (PL 

 XX.) 



When the larvae have emerged from one host fruit they do not enter 

 another except when numerous infested fruits are present in a single 

 container, and when all are more or less decayed. The writers have 

 not observed larvae, having emerged from their host, burrow into 

 sound fruits close by. Larvae, however, have been observed to burrow 

 into the decayed areas in other fruit touching the original host fruit, 

 and, being found there, have been recorded as attacking that fruit, 

 whereas their presence is accidental. 



The larva of the melon fly, in common with that of the Mediterra- 

 nean fruit fly, has a peculiar habit of jumping after it has left the 

 host. Larvae in the first two instars are unable to spring if taken 

 from the host. The mature larva arches its body so that it is able 

 with its mouth hooks to obtain a leverage on the posterior end of 

 the body. This done, with a sudden muscular relaxation it is able 

 to spring from a few to as many as 8 or 9 inches into the air or side- 

 ways. The larvae continue to jump after leaving the host until they 

 find a suitable place for pupation. They are not able to jump con- 



